I gave up and retreated to the house. But being the obsessive gardener that I am, I did not let it go. I hate using insect repellent because it it stings my skin, is sticky, smells bad and sometimes gets onto my lips or in my eyes - yuck! So, Google to the rescue!
In 30 seconds I found my answer - vanilla! Apparently gnats don't like it, and I have some so why not give it a try? I took about 1/8 a teaspoon real vanilla extract and rubbed it onto my neck, ears and forehead, grabbed the camera and went back outside. I was outside for the same amount of time I had been before - no gnats! And bonus, I smell like a cookie!